Pneumatic signal device



Jan. 3, 1939.1

R. R. STEVENS ET AL PNEUMATIC SIGNAL DEVICE Filed Aug. 29, 1956 I I I 23 7 14 33% 8 l2 *|s 56 i 37 9a 11 1 4 110 3} 2 38 5 29 \9 27 w 0%. a ATTORNEY I Patented Jan. 3, 1939 PNEUMATIC SIGNAL DEVICE Pa., a corporation of Pennsylvania Application August 29, 1936, Serial No. 98,508

8 Claims.

This invention relates to sound producing devices, and more particularly to the type operated by fluid under pressure.

One object of the invention is to provide an improved sound producer suitable for use as a signal on a vehicle and which is operative to sound a signal having desirable tonal quality as well as great penetrating power.

Another object of the invention is to provide a fluid pressure operated device of the above type which comprises at leasttwo sound producing means having different tonal characteristics and adapted to be suitably tuned or harmonized so as to create a blended warning note.

A further object of the invention is to provide a sound producer having an improved vibratory diaphragm.

In the accompanying drawing, the single figure is a diagrammatic sectional view of a sound producer constructed in accordance with the invention.

As shown in the drawing, there is provided a frusto-conical casing section I, which is secured to a mounting bracket 2 by any suitable means (not shown) and which has adjacent the smaller end thereof an annular flange 3, to which a casing section 4 is secured by bolts 5.

A vibratory diaphragm is provided, the peripheral portion of which is clamped between the casing section 4 and the flange 3 of casing section I, together with a centrally apertured disk 8 which is interposed between the diaphragm and the flange 3 for stiffening the diaphragm. The diaphragm i has a concentrically formed cylindrical portion 9 surrounding a central opening 9a therein and terminating in a flared flange portion H], which is fastened to the inner end of a cone element H by means of rivets I2. The peripheral portion of the cone element H is secured by rivets It to an annular supporting member I5 which is preferably made of resilient material such as rubber, and has its marginal portion clamped between a peripheral flange it formed on the conical casing section I and a clamping ring IT. The casing section I has an aperture I3 formed therein to provide communication between the atmosphere and the chamber intermediate the cone element H and the casing section I.

A convex screen l8, which may be made of closely woven wire mesh material, is provided for excluding dirt and foreign matter from the interior of the sound producer, the outer edge of the screen being interposed between the diaphragm I5 and the annular member I], which is secured to the flange It by any suitable means such as the bolts IS.

The casing section 4 has a relatively large central bore therein which is suitably threaded to receive a cylindrical seat member 2i, on the inner face of which is formed an annular seat 22 which is adapted to be engaged by the diaphragm l'adjacent the opening 9 therein. The seat 22 is adapted to be positioned as desired relative to the diaphragm l by adjustment of the screw threaded seat member 2!, a set screw 23 being provided for holding the seat member in its adjusted position. The seat and seat member together with the casing section d and the diaphragm l define 'a chamber 24, which is connected by way of a restricted port 25, a passage 26 in the casing section 4 and a pipe 21 with a source of fluid under pressure (not shown).

The cylindrical seat member 2! is provided with an outer annular groove 29, which is adapted to register with a passage 30 connected to the passage 26, and this groove communicates by way of a passage 32 with an interior annular groove 33 surrounding a central bore formed in the seat member.

The central bore within the seat member 2| is screw-threaded to receive a tubular element 35, which has formed therein an elongated chamber 36 closed at one end by a wall 3?, and surrounded at the other end by an annular rib portion 38, which extends into the opening 9a of the diaphragm l. The tubular element 35 is adapted to be adjusted as desired with respect to the seat member 2|, and has formed therein a plurality of passages is, one of which is shown. These passages are spaced apart circumferentially of the element 35 and register with the interior groove 33 in the seat member and open at a shoulder 4| of the element 35 outwardly of the rib 3B. The fluid discharged from the passages it is thus directed at the opening 90. within the diaphragm l, as shown in the drawing.

Associated with the tubular element 35 is a fluid pressure resonant device comprising a whistle bell 43, which is mounted coaxially with the element 35 by means of a stem 44 having one end secured to the bell and the other end extending through a suitably threaded bore in the end Wall 3? of the eleme -t 35. The whistle bell 23 is of somewhat larger diameter than the rib 38, and a sharp annular edge 45 is formed on the open end of the bell vadjacent the rib 38. This end of the whistle bell i3 is slightly flared so as to present the sharp edge thereof toward the juncture of the diaphragm l and seat 22, and in the path of fluid under pressure discharged from the passages 40 in the manner hereinafter explained.

The proper spacing of the edge 45 of the whistle bell 43 relative to the rib 38 is provided by adjustment of the screw-threaded stem 44, which is adapted to be held in the adjusted position by means of a lock nut 46.

In operation, fluid under pressure is supplied through the pipe 21, passage 26 and restricted passage 25 to the chamber 24 and quickly builds up sufficient fluid pressure therein to force the diaphragm I away from the seat 22 against the opposing force of the reinforcing disk 8, the cone i l and flexible member l5 which yields slightly to permit such movement. On movement of the diaphragm 7 away from the seat rib 22, fluid under pressure may escape from the chamber 24 to the passage 9a through the central portion of the diaphragm 1.

Because of the inertia of the diaphragm 1 and the cone I l, the diaphragm 1 will be thus moved far enough from the seat 22 to permit venting of fluid under pressure from the chamber 24 at a faster rate than that of flow of fluid to the chamber 24 by way of the restricted passage 25. Consequently the pressure of fluid acting on the diaphragm 1 is rapidly reduced and the diaphragm then moves into engagement with the seat 22, aided by the disk 8 so as to cut off the release of fluid from the chamber 24.

The pressure of the fluid in the chamber 24 will then be increased by flow thereto through the restricted passage 25 until the force exerted on the diaphragm 1 is great enough to again move the diaphragm away from the seat rib 22.

The rapidly repeated unseating and seating of the diaphragm I thus causes the diaphragm and the relatively large cone ll secured thereto to vibrate at a predetermined frequency, producing corresponding sound vibrations of the air adjacent said elements. The pitch and tonal quality of the sound produced are determined by the proportions of the diaphragm 7 and cone H and by the setting of the seat 22 relative to the diaphragm.

During operation of the diaphragm I as just described, the fluid under pressure released from the chamber 24 upon unseating of the diaphragm impinges against the sharp projecting edge 45 of the whistle bell 43, thereby setting up alternating condensations and rarefactions of the air column within the bell and the adjacent chamber 36 so as to sound a clear note of a pitch harmonizing that of the sound produced by the vibrating diaphragm.

At the same time fluid under pressure is: supplied at a constant rate from the passage 26 through the passagetfl, the groove 29, passage 32 and the groove 33 in the element 2|, and thence through the passages 40 to impinge against the edge 45 of the whistle bell 43 to supplement the fluid under pressure periodically discharged from the chamber 24, thereby insuring operation of the whistle to produce a substantially steady or sustained note.

The tonal quality of the sound produced by the resonant sound producing means is determined by the space between the end of the whistle bell 23 and the rib 38 on the tubular element 35, and this space may be adjustably varied by varying the position of the stem 44 relative to the tubular element 35.

It will be understood that the diaphragm and whistle elements of the sound producing device are so proportioned and arranged as to be 00- operative to produce a multiple note, resonance being obtained by the large cone associated therewith.

If desired, the edge 45 of the whistle bell 43 may be positioned out of the path of fluid under pressure discharged from the-chamber 24 past the diaphragm 1, and thus arranged to be operative solely by fluid under pressure supplied from the passages 40. This may be accomplished by turning the screw-threaded element 35 so as to shift said element to the left with respect to the member 2! as shown in the drawing, until the edge 45 on whistle bell 43 is positioned within seat rib 22. On the other hand, the connected passages 30 and 40 may be omitted and the whistle bell43 rendered operative only by the fluid under pressure released from the chamber 24 during operation of the diaphragm I, either of these embodiments being entirely within the spirit of my invention.

The invention thus provides an improved sound producing device of simple and inexpensive construction, and which is operative by fluid under pressure to sound a dual note made up of harmonizing tones separately produced and blended to create a distinctive warning sound.

While one illustrative embodiment of our invention has been described in detail, it is not our intention to limit its scope to this embodiment or otherwise than by the terms of the appended claims.

Having now described our invention, What we claim as new and desire to secure by Letters Patent, is:

l. A sound producing device comprising a casing having a chamber and an annular seat disposed adjacent said chamber, a vibratory diaphragm mounted within said casing, said diaphragm having a central aperture and a portion adjacent thereto adapted alternately to engage and disengage said seat, means for supplying fluid under pressure through a restricted port to said chamber at a face of said diaphragm outwardly of said seat for operating said diaphragm, and a relatively large frusto-conical resonator resiliently mounted on the casing and having the smaller end thereof rigidly secured to said diaphragm.

2. A sound producing device comprising a cas ing having formed therein a seat and a chamber; a fluid pressure operative vibratory diaphragm having a peripheral portion secured to the casing, a central aperture and a portion adjacent said aperture adapted alternately to engage and disengage said seat to control the release of fluid from the chamber at the face of the diaphragm outwardly of the seat; a conical resonator having the small end thereof secured to said portion of the diaphragm adjacent the aperture; a flexible annular member securing the large end of said resonator to the casing; and means for adjusting said seat relatively to said diaphragm to vary the sound produced during operation thereof.

3. A sound producing device comprising, in combination, fluid pressure resonant means, means for directing a substantially constant flow of fluid under pressure to said fluid pressure resonant means to cause said means to produce one sound, and means for directing an intermit- 4. A sound producing device comprising, in combination, a casing, fluid pressure resonant means carried thereby, fluid pressure directing means in said casing including a communication adapted to be supplied with fluid under pressure and terminating in two parallel branch passages, one of said branch passages being adapted to direct a constant flow of fluid under pressure against said-fluid pressure resonant means for causing it to produce one sound, and a vibratory diaphragm mounted in said casing and operative by flow of fluid to the other branch passage for eflecting an intermittent flow of fluid under pressure against said fluid pressure resonant means, said fluid pressure resonant means being thereby actuated to produce another sound combining with the first mentioned sound to produce a multiple note.

5. A sound producing device comprising, in combination, a casing, fluid pressure resonant means carried thereby, fluid pressure directing means in said casing including a communication adapted to be supplied with fluid under pressure and terminating in two parallel branch passages, one of said branch'passages being adapted to direct a constant flow of fluid under pressure against said fluid pressure resonant means to cause it to produce one sound, the other of said branch passages having a restricted flow area, and a vibratory diaphragm mounted in said casing and operative by flow of fluid through said restricted branch passage for effecting an intermittent flow of fluid under pressure against said fluid pressure resonant means to cause said resonant means to also produce a different sound, the two sounds thus produced by the fluid pressure resonant means combining to produce a resultant sound.

6. A sound producing device comprising a casing having a chamber and a seat rib defining a wall of said chamber, a fluid pressure operative vibratory diaphragm secured within said casing and having a central aperture, said diaphragm being adapted alternately to engage and disengage said seat rib to control the flow of fluid under pressure from said chamber past said seat rib and through said aperture, fluid pressure resonant means responsive to the fluctuating pressure of fluid periodically released by said diaphragm, and means positioning said fluid pressure resonant means within said aperture in the path of fluid under pressure discharged by operation of said diaphragm, whereby the sound Waves produced by said diaphragm and said resonant means are blended into a multiple note.

7. A sound producing device comprising a casing having a chamber, a vibratory diaphragm carried by said casing and subject to the pressure of fluid in said chamber, a member adjustably mounted in said casing and having a seat engageable by said diaphragm, said diaphragm being flexible into and out of engagement with said seat to control the release of fluid from said chamber, and fluid pressure resonant means adjustably mounted on said member and responsive to fluid under pressure released from said chamher during operation of said diaphragm for generating sound of a pitch determined by the rate of vibration of the diaphragm, the sound Waves produced by said diaphragm and resonant means being blended into a dual note.

8. A sound producing device comprising a casing having an annular chamber and an annular seat forming an inner wall of said chamber, a vibratory diaphragm carried by said casing and subject to the pressure of fluid in said chamber, said diaphragm having a central opening and a portion adjacent said opening movable into and out of engagement with said seat for controlling the release of fluid from said chamber through said opening, a fluid pressure resonant element mounted within said opening and having a sharp annular edge aligned for impingement thereon of fluid under pressure released from said chamber during the operation of said diaphragm to generate sound of a quality determined by the rate of fluctuation of the pressure of fluid discharged by said diaphragm, and means for supplying fluid under pressure to said chamber.

ROY R. STEVENS. GERALD C. CROUSHORE. 

